To send transactional SMS messages programatically, it's important to first identify what and where the list and message IDs are. The methods to get phone lists and list messages allow you to retrieve these IDs through the API calls. These IDs can also be found in the application by following the below steps.
Navigate from the home menu to the Short Code Activity Dashboard.
Navigate to the Dashboard Metrics.
Click View More on Transactional Messages.
Store these IDs for use in your test calls.